Message ID | 20221011083547.1831389-5-yukuai1@huaweicloud.com (mailing list archive) |
---|---|
State | New, archived |
Headers | show |
Series | blk-iocost: some random patches to improve iocost | expand |
On Tue, Oct 11, 2022 at 04:35:46PM +0800, Yu Kuai wrote: > From: Yu Kuai <yukuai3@huawei.com> > > In this special case, there is no need to throttle io. > > Signed-off-by: Yu Kuai <yukuai3@huawei.com> > --- > block/blk-iocost.c | 9 +++++++-- > 1 file changed, 7 insertions(+), 2 deletions(-) > > diff --git a/block/blk-iocost.c b/block/blk-iocost.c > index 5acc5f13bbd6..32e7e416d67c 100644 > --- a/block/blk-iocost.c > +++ b/block/blk-iocost.c > @@ -2564,8 +2564,13 @@ static void ioc_rqos_throttle(struct rq_qos *rqos, struct bio *bio) > bool use_debt, ioc_locked; > unsigned long flags; > > - /* bypass IOs if disabled, still initializing, or for root cgroup */ > - if (!ioc->enabled || !iocg || !iocg->level) > + /* > + * bypass IOs if disabled, still initializing, for root cgroup, > + * or the cgroup is the only cgroup with io. > + */ > + if (!ioc->enabled || !iocg || !iocg->level || > + (iocg->hweight_inuse == WEIGHT_ONE && > + atomic_read(&ioc->hweight_gen) == iocg->hweight_gen)) I'm not sure about this one. Bypassing here means that we lose track of how much IO it's issuing which can affect future throttling decisions, right? Thanks.
Hi, Tejun! 在 2022/10/12 1:02, Tejun Heo 写道: > On Tue, Oct 11, 2022 at 04:35:46PM +0800, Yu Kuai wrote: >> From: Yu Kuai <yukuai3@huawei.com> >> >> In this special case, there is no need to throttle io. >> >> Signed-off-by: Yu Kuai <yukuai3@huawei.com> >> --- >> block/blk-iocost.c | 9 +++++++-- >> 1 file changed, 7 insertions(+), 2 deletions(-) >> >> diff --git a/block/blk-iocost.c b/block/blk-iocost.c >> index 5acc5f13bbd6..32e7e416d67c 100644 >> --- a/block/blk-iocost.c >> +++ b/block/blk-iocost.c >> @@ -2564,8 +2564,13 @@ static void ioc_rqos_throttle(struct rq_qos *rqos, struct bio *bio) >> bool use_debt, ioc_locked; >> unsigned long flags; >> >> - /* bypass IOs if disabled, still initializing, or for root cgroup */ >> - if (!ioc->enabled || !iocg || !iocg->level) >> + /* >> + * bypass IOs if disabled, still initializing, for root cgroup, >> + * or the cgroup is the only cgroup with io. >> + */ >> + if (!ioc->enabled || !iocg || !iocg->level || >> + (iocg->hweight_inuse == WEIGHT_ONE && >> + atomic_read(&ioc->hweight_gen) == iocg->hweight_gen)) > > I'm not sure about this one. Bypassing here means that we lose track of how > much IO it's issuing which can affect future throttling decisions, right? Yes, you're right, this patch doesn't look good in this case. The reason why I tried to do this is because during test, I found that io performance is affected when I only issue io from one cgroup(only happened in some environment with default configuration), and I found out that each io is throttled for some time before dispatching. Perhaps a suitable configuration can avoid this problem. Thanks, Kuai > > Thanks. >
On Wed, Oct 12, 2022 at 09:33:46AM +0800, Yu Kuai wrote:
> Perhaps a suitable configuration can avoid this problem.
Yeah, iocost is a throttling controller. The default parameters try to be
adaptive but it really needs benchmarked parameters to work properly.
Thanks.
diff --git a/block/blk-iocost.c b/block/blk-iocost.c index 5acc5f13bbd6..32e7e416d67c 100644 --- a/block/blk-iocost.c +++ b/block/blk-iocost.c @@ -2564,8 +2564,13 @@ static void ioc_rqos_throttle(struct rq_qos *rqos, struct bio *bio) bool use_debt, ioc_locked; unsigned long flags; - /* bypass IOs if disabled, still initializing, or for root cgroup */ - if (!ioc->enabled || !iocg || !iocg->level) + /* + * bypass IOs if disabled, still initializing, for root cgroup, + * or the cgroup is the only cgroup with io. + */ + if (!ioc->enabled || !iocg || !iocg->level || + (iocg->hweight_inuse == WEIGHT_ONE && + atomic_read(&ioc->hweight_gen) == iocg->hweight_gen)) return; /* calculate the absolute vtime cost */